Yeah... It's kinda weird to receive a DM from a stranger who just said "hi" without any other context for it.
At the same time, they could be foreign or neurodivergent or took a huge chance of just shooting out a DM to you. Personally, I feel for them in this situation because you're really playing a game too hard here. Whether or not this person was genuine, which they seem to be (just super awkward), I don't like it when people toy with artists who are trying to collab or make commission. Hell, even just networking is a burden because everyone comes at you with a pitchfork OR just straight up ignores you.
I'm not saying they went about it perfectly. But I didn't appreciate the hoops you sent them through. As an artist myself who has had to do some major networking to freelance enough for rent each month, I've gotten nasty responses and swaths of lengthy emails that were a big insulting waste of my time and energy. Especially when a client tells me, "Ohhh? You want money? What if i DIDN'T pay you, but you worked your ass off for me anyways?" And even, "Ah, the invoice IS what we talked about originally... but what if I paid you less instead now that you've finished 40 hours of work for me?" It's degrading.
Now, you weren't being legitimate, and I understand you all think this is super funny... but that's still a person who contacted you and thought you were being serious in working with them.
Please don't do this again. Next time, just ignore them, or AT LEAST be straightforward with them. Like, this isn't very funny toying with people.